Finding TDC

[Mr Morris]

Hello, I was just wondering how to find TDC without the timing marks? I am fitting a new distributor and after doing so would like to check the timing and so on so that it's all as it should be. Problem is, I dont have the marks to show where TDC is.

[Alec]

Hello Mr. Morris,

are you sure there is no timing pointer, maybe underneath and a corresponding nick on the pulley?

To accurately find TDC requires the head to be removed, but if you are careful you can get near enough to start setting the timing up by putting a rod in number one plug hole. Road test after setting and adjust until it just penks then back off a shde so it doesn't.

Alec

[Mr Morris]

Hi Alec, there are no marks I can see - I've had a really good luck around. I will try what you said below - do you mean number 1 is down its near enough?

[kennatt]

take the rocker cover off and take out spark plugs, so engine can be turned easily turn take off dizzy cap turn engine until you see no 4 vavles inlet and exhaust rocking ie as you move the engine backwards and forward there is no delay in either valve moveing up or down put a screw driver into no one plug hole and again move engine very gently back and forth you will feel the top of the piston going up and down judge when it is right at the top,then look at the dizzy and the rotor will,should, be pointing at where no one plug lead is on the cap.This is top dead centre on no one.Then mark the bottom pully and engine block so that you know where it is in future',this will be near enough for you to set the static timing,then take it for a run advance the timing until the engine is pinking,a tingle type of rattle,when you give it the gas then slowly back the dizzy off ie retarding the timing until the pinking just stops,thats about where you want it to be, if you set it like this it dosent matter if tdc is slightly out you will still get the timing spot on, good luck

[robedney]

You can simplify this a bit by just pulling #1 plug and the dizzy cap. Stick a screwdriver in #1 cylinder and turn the engine over by hand until the rotor is pointing at the #1 plug wire AND the piston is at the top of it's travel. Rock back and forth a bit to find the high spot by watching the screwdriver.

Now mark this on your main pulley and on the timing chain cover. One of those bright yellow paint pens is ideal for this. That's close enough to set static timing and get the car running. The actual timing spec is probably something like 4 or 5 degrees BTDC, but the seat of the pants advance till pinking is the way to go.

If your fan belt is reasonably tight and you've got one plug pulled, you can very likely rotate the engine simply by grabbing the fan blades (of course the trans is in neutral). If the blades turn but the engine doesn't, reach down with one hand and put some inward pressure on the belt. Don't stick the screwdriver in until the rotor is pointing at number one -- you don't want to run the piston up into a screwdriver wedged at an angle in the cylinder!

[bmcecosse]

Don't use a screwdriver - better with something nice and fragile, like a chop stick or a drinking straw - just in case of accidents!

[Roni]

Another method is to use something like this as a stop.
[frame][/frame]
It is an old plug with a rocker stud firmly attached inside.
Rotate the motor so the piston is away from the top, fit this, gently rotate the motor until the piston just touches the stop and put a mark on the pulley.
Rotate the motor backwards until the same happens and put another mark on the pulley.
Half way between the marks is TDC. This is an accurate way to find TDC.
I used this method to put new marks on the pulley when I replaced the timing cover for a tensioner type, with the pointers above the pulley. (No more lying on the floor trying to see timing marks).
Interestingly, before I took the old original cover off, I checked that. It was 2 deg out.

[bmcecosse]

And -that 2 degrees mattered how????

[Roni]

The timing marks being out 2 deg would only matter if you were a strict "always set the timing by what the manual says" person and not the "rotate the dist until it pinks and then back it off a little" person. The motor tells you what it wants.
Also, if you were timing in a cam and using an inaccurate TDC mark to do it from.

[bmcecosse]

No advantage to 'timing in a cam' - again - it would be 'timed in' against some arbitrary setting that would not necessarily be relevant to that engine.....or to the desired characteristics. One setting for max power - another for good torque with slightly less max power. Unless almost unlimited access to an engine dyno - just time cams in dot to dot!